1. Field of the Invention
The present invention relates to a data transmission/reception technique in a 10 Gbps optical fiber channel and a physical layer of a 10 Gbps Ethernet, and more particularly to an apparatus and a method for carrying out a deskew among multiple lanes for use in a division transmission of large-capacity data, which can parallel process multiple lanes having a bit rate of several Gbps by carrying out a deskew among the multiple lanes in a case of the division transmission of the larger-capacity data and performing a high-speed transmission of more than the bit rate of 10 Gbps.
2. Description of the Related Art
A communication environment mainly relying on a local area network (LAN) needs an increased bandwidth in these days but there are limitations in an existing 10/100 Mbps Ethernet being constructed. Accordingly, an Ethernet system having communication capacity of more than a bit rate of 1 Gbps is strongly needed.
In response to such a need, a 10 Gbps Ethernet system has been developed. A physical layer of a 10 GBASE-X 10 Gbps Ethernet system such as the 10 Gbps Ethernet system is made up of a physical coding sublayer (PCS), a physical media attachment (PMA) sublayer and a physical media dependent (PMD) sublayer.
Among these sublayers, the PCS is used for parallel processing four 8B/10B lanes.
However, when an optical module transmits data over the PCS and the PMA, the data is transmitted to the four lanes separated from each other after the data is coded, the four lanes acting as one data channel having a bit rate of 10 Gbps. At this time, a skew among parallel lanes is caused in a reception side.
As described above, a division transmission of large-capacity data is necessary for transmitting the data having a bit rate of more than 10 Gbps in a digital signal level but a conventional Gbps multi-channel technique can not address the skew among the lanes where one large-capacity channel is divisionally transmitted to the four lanes composed of independent character streams.
Because it has been limited to several Gbps communication, communication within the PCS is accomplished on a byte-by-byte basis (at every 10 bits after coding) and therefore that a deskew can only be implemented on a bit-by-bit basis. For the sake of the divisional transmission of a number of character streams in a high-speed data transmission of more than 10 Gbps, there is needed a new alignment method based on a byte-by-byte or character-by-character basis as well as a skew compensation based on a bit-by-bit basis within a bus. However, a practical alignment method for aligning the four 8B/10B lanes has not been suggested up to now.
For example, prior-art problems are as follows.
FIG. 1 is a block diagram illustrating a physical coding sublayer (PCS) of a prior-art 10 GBASE-X 10 Gbps Ethernet receiver. The PCS of the prior-art 10 GBASE-X 10 Gbps Ethernet is made up of a synchronization function block 101, a deskew function block 102 and a decoding function block 103.
The synchronization function block 101 receives control signals representing a detection of a signal on each lane and 10 bit parallel signals as data streams from a physical media attachment (PMA) sublayer and detects a comma character of an 8B/10B code contained in the received signals to output the control signals C1 representing a synchronization status of each lane, respectively, and the received data streams.
Thereafter, the deskew function block 102 receives the control signals C1 and the data streams to recognize whether alignment characters of the data streams appear in all the lanes and then outputs control signals C2 representing that the skew has been adjusted or has not been adjusted along with the data streams.
Finally, the decoding function block 103 decodes the data streams received from the deskew function block 102 to 8B/10B codes and provides a medium access control (MAC) part with the decoded data streams.
FIG. 2 is a flow chart illustrating a deskew process in the prior-art 10 GBASE-X 10 Gbps Ethernet receiver. If the synchronization function block 101 fails a reset or synchronization process (sync_status=‘FAIL’), a procedure of the deskew process enters step 201 of “loss_of_alignment” as an initial status, and a control signal “enable_deskew” of a TRUE signal is outputted to enable the deskew process at the above step 201.
However, when the control signal “enable_deskew” is the TRUE signal, there is no way in which the deskew process can be carried out. Where the deskew process is once applied to a character stream or the skew is generated in the character stream, an alignment status of the character stream is monitored. Then, it is recognized whether a character stream ∥A∥ aligned three times has been detected through the monitoring of the alignment status of the character stream, the character stream ∥A∥ being composed of four characters /A/ aligned in an 8B/10B code, and any information about the alignment status is reported. Conventionally, only the above description is known.
In other words, only a function of monitoring the alignment status and reporting the information about the alignment status is suggested in the prior art and the deskew cannot be accomplished in the prior art.
FIG. 3 is a timing chart showing output signals having a skew to be outputted from the synchronization function block 101 of the PCS contained in the prior-art 10 GBASE-X 10 Gbps Ethernet receiver. The data streams by the 8B/10B coding are transmitted to the four independent lanes. At this time, where the data streams are transmitted from a transmission function block of the PCS through an optical fiber channel and an electrical channel, the alignment characters (e.g., /A/) contained in the data streams have the skew at different times as shown in FIG. 3.
However, there is a problem that the skew among the lanes cannot be addressed by the prior art.